In the production of a usable synthesis gas by the combustion of a carbonaceous fuel mixture, the process is conducted most effectively under a high temperature and high pressure conditions. For example, for the production of a gas from a carbonaceous fuel such as particulated coal, coke or even oil, a preferred operating temperature range of about 2,000.degree. to 3,000.degree. F. is maintained at a pressure of between about 5 to 250 atmospheres. The harsh operating conditions experienced in such a process, and in partcular the wide temperature variations encountered, will impose a severe strain on many segments of the gasifier or reactor units.
The invention is addressed to an improvement in the structure of the gasifier, and particularly in the quench ring and the dip tube arrangement. The latter., by their functions, are exposed to the gasifier's maximum temperature conditions by virtue of the hot product gas which makes contact with these members as they pass from the reaction chamber.
U.S. Pat. No. 4,218,423 issued on Aug. 19, 1980 in the name of Robin et al, illustrates one form of quench ring and dip tube which can be improved through use of the present arrangement. U.S. Pat. No. 4,444,726 issued on Apr. 24, 1984 in the name of Crotty et al, also illustrates a dip tube and quench ring for a reactor vessel. In the latter, a portion of the gasifier's cooling system is insulated, but does not provide an effective barrier which would avoid contact between the hot effluent stream and the cold quench ring surface.
Among the problems encountered due to the high temperature conditions within the gasifier, is the developing of thermal stresses which often result in damage to the quench ring as a result of the ring's close proximity to the hot effluent stream. These problems are often manifested in the form of cracks and fissures which develop in parts of the quench ring. The latter usually in areas particularly where sharp corners are present such that any physical or thermal stress would be magnified and result in leakage of liquid coolant into the reactor chamber.
A further operational difficulty can be experienced in gasifiers as a result of the propensity of molten slag to harden and freeze in the gasifier's constricted throat. This phenomena results when the throat section becomes sufficiently cool to reduce the slag temperature as the latter flows out of the reaction chamber.
This undesirable chilling action can under particular circumstances, severely block the constricted throat opening, thereby precluding further operations.